Heart (cardiac) auscultation is a very old technique, which is still commonly used during medical examinations carried out by physicians. It is performed using a standard non-electronic stethoscope, an electronic analogue stethoscope or a modern digital stethoscope. Cardiac auscultation is based on auditory perception of sounds produced by the heart in certain areas of the human body. These sounds are often accompanied by special kind of maneuvers which enhance some significant sounds, clicks or murmurs produced by the heart muscle and the blood flow across heart valves. Cardiac auscultation is difficult to perform properly due to the limitations of human hearing.
A cardiac auscultation examination requires nearly perfect hearing and extensive experience of a physician in dealing with rare cases of heart abnormalities. However, while experience increases with age, hearing deteriorates. Furthermore, acoustic signals have very (low) small amplitude and a heart's activity is usually represented by very low frequencies which remain on the edge of human perception. Also, pathologies detectable via cardiac auscultation are rare, and therefore physicians are not able to compare various cases representative of a given pathology thereby making diagnosis even more difficult. That is, an ordinary physician usually does not have enough experience to determine the audible phenomena, e.g. whether the extra sounds, murmurs or clicks are pathological, or not.
Additionally, interpretation of the results of an auscultation exam is very subjective, because different doctors have different experience and hearing abilities. Cardiac auscultation also requires very good hearing, which is not very common among human population (while it is necessary to perform cardiac auscultation effectively). Since hearing and experience of each human being differ, result of the auscultation is often very subjective matter. Hence, in many cases Cardiac auscultation is not treated seriously among medical community despite its potential. For this reason, despite its potential, cardiac auscultation is treated as a preliminary overview of the patient's heart condition, rather than a source of reliable information for potential treatment.